Black Tank flush line leaking.

Just don't use it until you get back home and can properly address fixing it

Not using it is NOT going to cause issues with your black tank.
Just increase liquid to solids ratio and dump when FULL
Then add a few gallons of water back in after dumping so nothing dries out.

Are you getting water inside your rig? Or dripping from the underbelly? You will need to locate as near as possible the exact area where the water leak is coming from before opening up panels or walls.

The anti siphon/vacuum breaker valves, something like this, are notorious for leaking. They are typically mounted a foot or more above the floor level, under a bathroom vanity, under a kitchen sink, or (in my case) inside a wall behind the shower. There should be two water lines going to the valve, one flowing up and one flowing down.

Leaks in fittings, or possibly a leak in a piece of tubing, could be anywhere.

Couple years ago mine started leaking. My black tank flusher is located under the bathroom sink, so access was very easy for me. The check valve is also under the sink.

Mine was leaking at that place where the garden hose attaches. It had cracked. Replacement took about 15 minutes. Unscrew the pipe from the back side, and 3 screws on the outside. Pop in the new one, reattach hose-pipe on the inside, screw in 3 new screws on the outside with a little bit of caulking to seal it up from rain.

Old one:







New one in place:

I would guess a leaking vacuum breaker? I think they are usually near the water inlet fitting and are a couple of feet above the floor. Or maybe the PEX connection to the exterior water inlet fitting? Your TT has a slide on either side of the fridge - try taking the exterior access panel off and maybe it's hiding in there? I would expect the PEX line to the tank would be a clear run with no fittings. They sure crammed a lot of stuff in the short space between the slides!

I've pulled a fridge out before and it would help to be able build a temporary plywood shelf or cribbing to slide it out onto. You'd want a cap for the propane line too. Not that hard but I wouldn't want to do it while out on a trip. If you're near a Walmart or RV dealer/shop you could get a black tank wand and stick it down the toilet.

Our vacuum breaker is under the kitchen sink and accessible by removing a bank of drawers. I use our in-tank flusher all the time and would hate not being able to use it.